Raising the spectre of a "nuclear arms race in the most volatile region in the world", the US president predicted that if Tehran's apparent ambitions succeeded four or five countries in the Middle East would scramble to acquire nuclear weapons in a "free-for-all" .

"I think both the Iranian and the Israeli governments recognise that when the United States says it is unacceptable for Iran to have a nuclear weapon, we mean what we say," said Mr Obama.

He unequivocally dismissed Israeli fears that the US might resign itself to containing a nuclear Iran, telling The Atlantic magazine this ran "completely contrary" to his policy of nuclear non-proliferation.

"I think that the Israeli government recognises that, as president of the United States, I don't bluff," he said. "I also don't, as a matter of sound policy, go around advertising exactly what our intentions are."

Mr Obama emphasised that the current US approach included diplomatic pressure, political isolation and "unprecedented and crippling" economic sanctions.

But he also stressed a potential "military component", adding: "When I say we are not taking any option off the table we mean it. We are going to continue to apply pressure until Iran takes a different course."

Mr Obama claimed that the risk of an Iranian bomb being passed to terrorist groups – which Tehran would feel emboldened in supporting – was "profound", and that surrounding states would feel forced to follow suit.

"It is almost certain that other players in the region would feel it necessary to get their own nuclear weapons," he added. "So now you have the prospect of a nuclear arms race in the most volatile region in the world, one that is rife with unstable governments and sectarian tensions."

The president is due to meet Mr Netanyahu for a showdown at the White House on Monday amid mounting tensions between their two administrations over the Iranian crisis.

While Mr Obama is anxious to avoid being sucked into a fresh conflict months before the US presidential election, Israeli officials have threatened to pre-emptively strike Iran's nuclear facilities unless Washington delivers a more bellicose warning to Tehran.

Mr Netanyahu is said to be frustrated with mixed messages coming from Washington, warning from Ottawa on Friday evening that Israel has a right to defend itself. Gen. Martin Dempsey, the chairman of the joint chiefs of staff, last month cautioned that an attack on Iran now would destabilise the region.

Professor Daniel Byman, the director of the Center for Peace and Security Studies and a Middle East expert, said that Mr Obama was "ratcheting up his rhetoric" to "convince Israel that they are not on their own with this".

"His remarks show real concern in the administration that Israel is going to strike Iran in defiance of American pressure," said Prof Byman. "He has always had this threat on the table, but has never emphasised it quite so strongly.

"He is trying to convince Israel that he has not decided that the US will not attack Iran, ironically in the hope of putting off an Israeli strike and giving sanctions a little more time."

Mr Obama claimed in his interview that economic sanctions were placing Tehran in "a world of hurt". Earlier this week Jay Carney, his spokesman, made clear that Washington wanted to allow the sanctions to impact Tehran's decision-making.

"We believe that there is time and space to continue to pursue that approach," said Mr Carney, "even as we refuse and make clear that we do not take any option off the table in our effort to prevent Iran from acquiring a nuclear weapon."

Mr Obama said that the US and Israel were of the shared view that "Iran does not yet have a nuclear weapon and is not yet in a position to obtain a nuclear weapon without us having a pretty long lead time in which we will know that they are making that attempt".

Monday's talks come nine months after the last Washington meeting between the pair, which ended with the Israeli prime minister delivering a humiliating lecture to his host in front of television cameras in the Oval Office.

Mr Obama, who is frequently accused of being lukewarm towards the US-Israeli alliance, stressed that his message to the Israeli people was: "We've got Israel's back". However he appeared to acknowledge that his relationship with Mr Netanyahu was cool.